The new Audi S6sedan has been spied in southern Europe during development testing this week, ahead of an anticipated reveal later this year.

Spotted almost free of camouflage, we can distinguish this S6 prototype from normal versions of the A6 sedan thanks to the more aggressive bumper treatments front and rear, larger air intakes, along with the quad-tipped exhaust out back.

It's believed the new S6 will dump its current 4.0-litre twin-turbo V8 in favour of the new 2.9-litre bi-turbo V6 donk featured under the bonnet of the RS4 and RS5.

The motor in its current form develops 331kW of power and 600Nm of torque in the smaller RS4 and RS5, enough for 0-100km/h claims of 4.1 seconds and 3.9 seconds respectively. Expect the heavier S6 to hit triple figures in around 4.1-4.2 seconds with the same engine.

Should the twin-turbo V6 be the powertrain of choice, the S6 will send power to the ground via an eight-speed torque-converter auto and Audi's quattro all-wheel drive system.

Considering the new-generation Audi A6 was revealed just before this year's Geneva motor show, it's likely the S6 will make its debut in the coming months – perhaps around the same time as the Paris motor show in October.

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